Chemically amplified positive-type resist composition and resist pattern formation method

Abstract

The present invention provides a chemically amplified positive-type resist composition that can form a resist film with extremely high isolated space resolution, low LER, excellent rectangularity, and the ability to form a pattern that suppresses the effects of development loading and residue defects, and a method for forming a resist pattern using the chemically amplified positive-type resist composition. [Solution] A chemically amplified positive resist composition for electron beam lithography comprising (A) a base polymer, (B) a photoacid generator, and (C) a quencher, wherein (A) the base polymer comprises a polymer containing a predetermined phenolic hydroxyl group-containing unit, a predetermined aromatic ring-containing unit, and a predetermined phenolic hydroxyl group-containing unit, all repeating units of the polymer contained in the base polymer are repeating units having an aromatic ring skeleton, and the content ratio of (B) the acid generator to (C) the quencher ((B) / (C)) is less than 3 by mass ratio.

Description

[Technical Field]

[0001] The present invention relates to a chemically amplified positive-type resist composition and a resist pattern formation method. [Background technology]

[0002] In recent years, with the increasing integration of integrated circuits, there has been a demand for the formation of finer patterns. For processing patterns of 0.2 μm or less, chemically amplified resist compositions using acids as catalysts are mainly used. High-energy rays such as ultraviolet light, far ultraviolet light, extreme ultraviolet (EUV), and electron beams (EB) are used as exposure sources in this process. EB lithography, in particular, which is used as an ultra-fine processing technology, has become indispensable as a method for processing photomask blanks when creating photomasks for semiconductor manufacturing.

[0003] Generally, in EB lithography, EB drawing is performed without the use of a mask. In the case of positive-type lithography, micro-area EB is sequentially irradiated onto areas of the resist film other than those to be preserved, while in the case of negative-type lithography, micro-area EB is sequentially irradiated onto areas of the resist film to be preserved. In other words, because the entire area of ​​the processed surface is swept across the finely divided sections, it takes longer than batch exposure using a photomask, and a highly sensitive resist film is required to maintain throughput. Particularly in the processing of photomask blanks, which is an important application, some photomask substrates have surface materials such as chromium oxide and other chromium compound films that can easily affect the pattern shape of the chemically amplified resist film. Therefore, maintaining a rectangular pattern profile of the resist film, regardless of the substrate type, is considered an important performance characteristic in order to maintain high resolution and shape after etching. Another important performance characteristic is a low line edge roughness (LER). In recent years, multibeam mask lighting (MBMW) lithography processes are sometimes used to process mask blanks in order to achieve miniaturization. In such cases, low-sensitivity resist compositions (high-dose regions) that are advantageous for roughness are used as the resist composition, and the optimization of resist compositions in this high-dose region has also attracted attention.

[0004] Various improvements have been made to control sensitivity and pattern profiles through the selection and combination of materials used in the resist composition, process conditions, and other factors. One such improvement is the suppression of acid diffusion, which has a significant impact on the resolution of the resist film. In photomask processing, it is required that the shape of the resulting resist pattern does not change depending on the time between exposure and heating. A major cause of time-dependent changes in the resist pattern shape is the diffusion of acid generated by exposure. This acid diffusion problem has been investigated extensively, not only in photomask processing but also in general resist compositions, as it significantly affects sensitivity and resolution.

[0005] Patent documents 1 and 2 describe examples of reducing LER by increasing the bulk of the acid generated from an acid generator to suppress acid diffusion. However, since the suppression of acid diffusion with such acid generators is still insufficient, there has been a need for the development of an acid generator that exhibits even less acid diffusion.

[0006] Furthermore, Patent Document 3 describes an example of controlling acid diffusion by introducing repeating units having a sulfonium structure that generates sulfonic acid upon exposure into a polymer used in a resist composition. This method of suppressing acid diffusion by introducing repeating units that generate acid upon exposure into a base polymer is effective in obtaining a pattern with a small LER. However, in some cases, base polymers containing such repeating units that generate acid upon exposure may have problems with solubility in organic solvents, depending on the structure and introduction rate of the units.

[0007] Polymers containing a large amount of aromatic skeletons with acidic side chains, such as polyhydroxystyrene, are useful as base polymers for KrF lithography resist compositions. However, they exhibit significant absorption for light around 200 nm, and therefore have not been used as base polymers for ArF lithography resist compositions. Nevertheless, they are important materials for EB lithography and EUV lithography resist compositions, which are promising techniques for forming patterns smaller than the processing limit of ArF excimer laser light, due to their high etching resistance.

[0008] For positive-type EB lithography resist compositions and EUV lithography resist compositions, the base polymers mainly used are those that can be solubilized in an alkaline developer by using an acid generated by irradiating a photoacid generator with high-energy rays as a catalyst to deprotect the acid-unstable groups that mask the acidic functional groups of the phenol side chains of the base polymer. As acid-unstable groups, tertiary alkyl groups and tert-butoxycarbonyl groups have been used, as well as acetal groups, which have relatively low activation energies (Patent Documents 4-7).

[0009] However, while acetal groups have the advantage of yielding highly sensitive resist films, in the MBMW lithography process used to fabricate photomasks with a tip narrower than 10 nm, in particular, because the resist film thickness is in the thin-film region of 100 nm or less and the lithography is performed in the high-dose region with high irradiation energy, if the acetal is bulky and has high reactivity, deprotection reactions can occur even in the unexposed parts of the resist film, leaving residue even in the exposed parts. This can lead to problems such as degradation of isolated space resolution and LER, which are important in positive-type resist compositions, and the occurrence of defects.

[0010] Furthermore, in the development process of photomask manufacturing, a phenomenon called development loading occurs, in which there are differences in the dimensional finish of the pattern between densely and sparsely patterned areas on the photomask. In other words, development loading causes an uneven distribution of the dimensional finish of the pattern depending on the pattern distribution of the surrounding area. Factors contributing to this include differences in the desorption reaction during acid generation due to the energy difference of the electroluminescent beam (EB), and differences in the dissolution rate of the densely and sparsely patterned areas in the alkaline developer. As one improvement, Patent Document 8 describes a method of adjusting the incident dose amount in the EB writing apparatus to irradiate the photomask with EB and draw a pattern, thereby correcting for development loading. However, conventional correction methods did not adequately consider the development loading phenomenon. Therefore, conventional correction methods had poor accuracy in correcting for development loading. To address this, methods have been developed to improve the drawing method for drawing resist films and the development method after patterning, as described in Patent Documents 9 and 10. However, these methods are insufficient for uniformly distributing sparse and dense fine patterns in the advanced generation, and there has been a need for improved resist compositions that can achieve high resolution and reduce development loading and residue defects even in the advanced generation. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2009-53518 [Patent Document 2] Japanese Patent Publication No. 2010-100604 [Patent Document 3] Japanese Patent Publication No. 2011-22564 [Patent Document 4] Patent No. 39811830 [Patent Document 5] Patent No. 5385017 [Patent Document 6] International Publication No. 2019-167419 [Patent Document 7] Patent No. 6987873 [Patent Document 8] Japanese Patent Publication No. 2007-150243 [Patent Document 9] Patent No. 5443548 [Patent Document 10] Patent No. 6281244 [Overview of the project] [Problems that the invention aims to solve]

[0012] The present invention has been made to solve the aforementioned problems and aims to provide a chemically amplified positive-type resist composition that can form a resist film having extremely high isolated space resolution, a small LER, excellent rectangularity, and the ability to form a pattern that suppresses the effects of development loading and residue defects, and a method for forming a resist pattern using the chemically amplified positive-type resist composition. [Means for solving the problem]

[0013] As a result of diligent research to achieve the above objective, the present inventors have found that by creating a resist composition comprising a base polymer using a specific acetal-type acid-unstable group, a photoacid generator, and a quencher, and controlling the ratio of the photoacid generator to the quencher, it is possible to obtain a pattern that exhibits good isolated space resolution, pattern shape, and LER even in the high-dose region, while suppressing the effects of development loading and residue defects, thus leading to the present invention.

[0014] In other words, the present invention provides the following chemically amplified positive-type resist composition and resist pattern formation method. 1. (A) Base polymer, (B) Photoacid generator, and (C) Quencher, with an electron beam exposure of 50 μC / cm². 2 The above describes a chemically amplified positive resist composition for electron beam lithography, (A) The base polymer comprises a polymer containing a phenolic hydroxyl group-containing unit represented by the following formula (A1), an aromatic ring-containing unit represented by either of the following formulas (A2) and (A4), and a phenolic hydroxyl group-containing unit protected by an acid-unstable group represented by the following formula (A5), wherein all repeating units of the polymer contained in the base polymer are repeating units having an aromatic ring skeleton. A chemically amplified positive resist composition in which the ratio of (B) photoacid generator to (C) quencher ((B) / (C)) is less than 3 by mass ratio. [ka] (In the formula, a1 is an integer satisfying 0 ≤ a1 ≤ 5 + 2a3 - a2. a2 is an integer between 1 and 3. a3 is an integer between 0 and 2.) R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 A is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain. A 1is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- of the saturated hydrocarbylene group may be substituted with -O-. R 1 is a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom. )

Chemical formula

Chemical formula

[0016] The present invention will be described in detail below. In the following description, depending on the structure represented by the chemical formula, an asymmetric carbon may be present, and enantiomers or diastereomers may exist. In such cases, a single formula will represent all of these isomers. These isomers may be used individually or as a mixture.

[0017] [Chemically amplified positive-type resist composition] The chemically amplified positive resist composition of the present invention comprises (A) a base polymer, (B) a photoacid generator, and (C) a quencher.

[0018] [(A) Base polymer] The base polymer of component (A) contains a polymer comprising a phenolic hydroxyl group-containing unit represented by the following formula (A1) (hereinafter also referred to as repeating unit A1). [ka]

[0019] In equation (A1), a1 is an integer satisfying 0 ≤ a1 ≤ 5 + 2a3 - a2. a2 is an integer between 1 and 3. a3 is an integer between 0 and 2.

[0020] In formula (A1), RA These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0021] In formula (A1), X 1 A is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain.

[0022] In formula (A1), A 1 The saturated hydrocarbylene group is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and some of the -CH2- atoms of the saturated hydrocarbylene group may be substituted with -O- atoms. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples include alkanediyl groups having 1 to 10 carbon atoms such as methylene groups, ethane-1,2-diyl groups, propane-1,3-diyl groups, butane-1,4-diyl groups, pentane-1,5-diyl groups, hexane-1,6-diyl groups, and structural isomers thereof; cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms such as cyclopropanediyl groups, cyclobutanediyl groups, cyclopentanediyl groups, and cyclohexanediyl groups; and groups obtained by combining these.

[0023] In formula (A1), R 1 This is a halogen atom, a saturated hydrocarbyl carbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms that may be substituted with a halogen atom. The saturated hydrocarbyl group, and the saturated hydrocarbyl portion of the saturated hydrocarbyl carbonyloxy group and saturated hydrocarbyloxy group may be linear, branched, or cyclic. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, and hexyl groups; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl groups; and groups obtained by combining these. If the number of carbon atoms is below the upper limit, the solubility in alkaline developer is good. When a1 is 2 or more, each R 1They may be the same as or different from each other.

[0024] X 1 and A 1 When both are single bonds, preferred examples of repeating unit A1 include units derived from 3-hydroxystyrene, 4-hydroxystyrene, 5-hydroxy-2-vinylnaphthalene, 6-hydroxy-2-vinylnaphthalene, etc. Of these, repeating units represented by the following formula (A1-1) are more preferred. [ka] (In the formula, R A (and a2 are the same as above.)

[0025] X 1 When the bond is not a single bond, preferred examples of the repeating unit A1 are, but are not limited to, those shown below. Note that in the following formula, R A This is the same as described above. [ka]

[0026] [ka]

[0027] The repeating unit A1 is preferably introduced in an amount of 30 to 90 mol%, and more preferably in an amount of 40 to 85 mol%, of the total repeating units of the polymer contained in the base polymer. However, if the polymer described later includes at least one of the repeating units represented by formula (A2) and formula (A3) that provide high etching resistance, and the unit has a phenolic hydroxyl group as a substituent, then it is preferable that the ratio of these units is also included within the above range. The repeating unit A1 may be used alone or in combination of two or more types.

[0028] The polymer further includes at least one selected from the aromatic ring-containing units represented by the following formula (A2) (hereinafter also referred to as repeating unit A2), the aromatic ring-containing units represented by the following formula (A3) (hereinafter also referred to as repeating unit A3), and the aromatic ring-containing units represented by the following formula (A4) (hereinafter also referred to as repeating unit A4). [ka]

[0029] In equations (A2) and (A3), b and c are each independent integers between 0 and 4.

[0030] In formulas (A2) and (A3), R 2 and R 3 Each of these is independently a hydroxyl group, a halogen atom, a saturated hydrocarbyl carbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 8 carbon atoms that may be substituted with a halogen atom. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, and saturated hydrocarbyl carbonyloxy group may be linear, branched, or cyclic. When b is 2 or more, each R 2 They may be the same or different from each other. When c is 2 or more, each R 3 They may be the same as or different from each other.

[0031] In formula (A4), R A The same applies as above. d1 is an integer between 0 and 5. d2 is an integer between 0 and 2.

[0032] In formula (A4), R 4The saturated hydrocarbyl group is an acetyl group, a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxyhydrocarbyl group having 2 to 20 carbon atoms, a saturated hydrocarbylthiohydrocarbyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group, or a cyano group, and if d2 is 1 or 2, it may also be a hydroxyl group. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, saturated hydrocarbyloxyhydrocarbyl group, and saturated hydrocarbylthiohydrocarbyl group may be linear, branched, or cyclic. When d1 is 2 or more, each R 4 They may be the same as or different from each other.

[0033] In formula (A4), X 2 A is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain.

[0034] In formula (A4), A 2 A is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and some of the -CH2- in the saturated hydrocarbylene group may be substituted with -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and a specific example thereof is A in formula (A1). 1 Examples similar to those given in the explanation can be cited.

[0035] When repeating units A2 to A4 are used, in addition to the etching resistance of the aromatic rings, the addition of a ring structure to the main chain enhances the resistance to EB irradiation during etching and pattern inspection.

[0036] To obtain the effect of improving etching resistance, it is preferable that repeating units A2 to A4 be introduced in an amount of 5 mol% or more of the total repeating units of the polymer contained in the base polymer. Furthermore, it is preferable that repeating units A2 to A4 be introduced in an amount of 25 mol% or less of the total repeating units of the polymer contained in the base polymer, and more preferably 20 mol% or less. If the amount introduced is 25 mol% or less when there is no functional group or when the functional group is not a hydroxyl group, it is preferable because there is no risk of development defects occurring. Repeating units A2 to A4 may be used individually or in combination of two or more types.

[0037] The content of at least one repeating unit selected from repeating units A1 and A2 to A4 in the total repeating units of the polymer contained in the base polymer is preferably 50 mol% or more, and more preferably 60 mol% or more.

[0038] The polymer further comprises a phenolic hydroxyl group-containing unit protected by an acid-unstable group represented by the following formula (A5) (hereinafter also referred to as repeating unit A5). [ka]

[0039] In formula (A5), R A The same applies as above. e1 is an integer satisfying 0 ≤ e1 ≤ 5 + 2e3 - e2. e2 is an integer between 1 and 3. e3 is an integer between 0 and 2.

[0040] In formula (A5), X 3 A is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain.

[0041] In formula (A5), A 3A is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and some of the -CH2- in the saturated hydrocarbylene group may be substituted with -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and a specific example thereof is A in formula (A1). 1 Examples similar to those given in the explanation can be cited.

[0042] In formula (A5), R 5 This is a halogen atom, a saturated hydrocarbyl carbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms that may be substituted with a halogen atom. The saturated hydrocarbyl group, as well as the saturated hydrocarbyl portion of the saturated hydrocarbyl carbonyloxy group and the saturated hydrocarbyl oxy group, may be linear, branched, or cyclic, and a specific example thereof is R in formula (A1). 1 Examples similar to those given in the explanation can be cited. If the number of carbon atoms is below the upper limit, solubility in alkaline developer is good. When e1 is 2 or more, each R 5 They may be the same as or different from each other.

[0043] In formula (A5), R AL When e2 is 1, it is an acetal-type acid-unstable group represented by the following formula (A5-1), and when e2 is 2 or more, it is a hydrogen atom or an acetal-type acid-unstable group represented by the following formula (A5-1), but at least one of them is an acetal-type acid-unstable group represented by the following formula (A5-1). [ka]

[0044] In formula (A5-1), R L1 and R L2 Each of these is independently a saturated hydrocarbyl group having 1 to 3 carbon atoms, and R L1 and R L2 However, they may bond with each other to form a ring with the carbon atoms to which they are bonded.L3 These are hydrocarbyl groups with 1 to 5 carbon atoms. The dashed lines represent bonding bonds.

[0045] R L1 and R L2 The appropriate group is selected depending on the design of the sensitivity of the decomposition group to acid. If the design requires high sensitivity to pH changes and suppression of residue defects using relatively high reactivity, a linear alkyl group is selected. L1 and R L2 Specific examples include methyl, ethyl, n-propyl, and isopropyl groups, but the methyl group is preferred because it has optimal acid elimination performance. Also, R L1 and R L2 When these elements bond to each other and form a ring with the carbon atoms to which they are bonded, examples of such rings include cyclopentane rings and cyclohexane rings.

[0046] As an acetal structure, R L1 and R L2 It is preferable that the carbon atom to which the bond is made is a secondary carbon atom from the viewpoint of polymer stability and reactivity with acid. L1 and R L2 If the carbon atom to which it is bonded is a primary carbon atom, the reactivity is too high and the stability is poor, R L1 and R L2 When the carbon atom to which the compound is bonded is a tertiary carbon atom, the reactivity is poor and the reaction contrast decreases.

[0047] Among the aforementioned acetal-type acid-unstable groups, in order to obtain higher resolution, R L3Examples of acid-leading groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, and cyclopentyl groups, but more preferably methyl, ethyl, n-propyl, isopropyl, tert-butyl, and cyclopentyl groups. When the number of carbon atoms exceeds 6, the leached alcohol component becomes less soluble in alkaline developer due to the bulkiness of the acid-leading group, resulting in a deterioration of isospace resolution and a significant amount of residue after development, which is unfavorable for photomask processing in generations finer than 10 nm.

[0048] Methods for protecting polymers with acetal-type acid-unstable groups after polymerization include methods using vinyl ether and acid catalysts, and methods using acetalizing agents with haloalkoxy groups together with a base. Any of these methods can be used here.

[0049] For example, in the method using vinyl ether and an acid catalyst, examples of acid catalysts used in the reaction include methanesulfonic acid, tolfluoroacetic acid, oxalic acid, and pyridine methanesulfonic acid. The reaction temperature is preferably 5°C to 30°C, and the reaction time is 0.2 to 10 hours, preferably 0.5 to 6 hours.

[0050] Another method involves using an acetalizing agent containing a haloalkoxy group together with a base, in which the acetalizing agent containing the haloalkoxy group is added dropwise in the presence of a basic compound such as triethylamine. The reaction temperature in this case is -20 to 50°C, and the reaction time is 0.2 to 10 hours, preferably 0.5 to 6 hours.

[0051] However, in methods using acetalizing agents containing haloalkoxy groups together with a base, corrosive strong acids such as hydrochloric acid are generated, which can corrode metal manufacturing vessels and piping, and may result in the inclusion of metal components that cause defects in semiconductor products. In particular, in advanced generations, metal impurities in raw materials used in resist compositions are required to be 10 ppb or less, so a method using vinyl ether and an acid catalyst is preferred.

[0052] The repeating units protected by the acetal-type acid-unstable group are preferably introduced in an amount of 10 to 40 mol%, more preferably 10 to 35 mol%, and even more preferably 20 to 30 mol%, of the total repeating units of the polymer contained in the base polymer.

[0053] The base polymer may include, in addition to the polymer having the acetal-type acid-unstable group, a polymer having a known acid-unstable group other than the acetal-type acid-unstable group represented by formula (A5-1), such as a tertiary alkyl group or a tert-butoxycarbonyl group. In this case, the polymer having an acid-unstable group other than the acetal-type acid-unstable group represented by formula (A5-1) preferably includes a repeating unit having an acid-unstable group other than the acetal-type acid-unstable group represented by formula (A5-1) and repeating unit A1, and optionally includes repeating units A2 to A4. In order to exhibit the effects of the present invention, it is preferable that the proportion of the base polymer having the acetal-type acid-unstable group in the total base polymer contained in the chemically amplified positive resist composition of the present invention is 30% or more.

[0054] The aforementioned acetal-type acid-unstable group also has the effect of suppressing the effect of backscattering during EB lithography, therefore, 50 μC / cm 2 Preferably 80 μC / cm² 2 More preferably 100 μC / cm 2 Within the sensitivity range described above, the pattern shape exhibits rectangular performance without becoming a reverse taper.

[0055] The base polymer preferably has a weight-average molecular weight (Mw) of 1,000 to 20,000, and more preferably 3,000 to 9,000. If Mw is 1,000 or more, there is no risk of phenomena such as the pattern heads becoming rounded, reducing resolution, and LER degradation, as is conventionally known. On the other hand, if Mw is 20,000 or less, there is no risk of LER degradation, especially when forming patterns with a pattern line width of 100 nm or less. In this invention, Mw is a polystyrene-converted measurement value obtained by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or dimethylformamide (DMF) as a solvent.

[0056] The base polymer preferably has a narrow dispersion with a molecular weight distribution (Mw / Mn) of 1.0 to 2.0, preferably 1.0 to 1.9, and more preferably 1.0 to 1.8. When the dispersion is narrow in this way, no foreign matter is generated on the pattern or the shape of the pattern deteriorates after development.

[0057] Furthermore, regarding the base polymer design, the dissolution rate in the alkaline developer is preferably 10 nm / min or less, more preferably 7 nm / min or less, and even more preferably 5 nm / min or less. In advanced generations, when the coated film on the substrate is in the thin film region (100 nm or less), the effect of pattern film reduction on alkaline development becomes significant, and if the alkali dissolution rate of the polymer is greater than 10 nm / min, the pattern collapses, making it impossible to form fine patterns. This is particularly noticeable in the fabrication of photomasks, where defect-free conditions are required, as the development process tends to be more intense. In this invention, the dissolution rate of the base polymer in the alkaline developer is calculated from the amount of film reduction when a polymer solution (polymer concentration: 16.7 mass%, solvent: propylene glycol monomethyl ether acetate (PGMEA)) is spin-coated onto an 8-inch silicon wafer, baked at 100°C for 90 seconds to form a film with a thickness of 1000 nm, and then developed with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution at 23°C for 100 seconds.

[0058] [(B) Photoacid Generator] The chemically amplified positive resist composition of the present invention may contain a photoacid generator. The photoacid generator is not particularly limited as long as it is a compound that generates acid upon irradiation with high-energy rays. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxiimide, oxime-O-sulfonate type acid generators, and the like.

[0059] Specific examples of the photoacid generator include nonafluorobutanesulfonate, partially fluorinated sulfonates described in paragraphs

[0247] to

[0251] of Japanese Patent Publication No. 2012-189977, partially fluorinated sulfonates described in paragraphs

[0261] to

[0265] of Japanese Patent Publication No. 2013-101271, and those described in paragraphs

[0122] to

[0142] of Japanese Patent Publication No. 2008-111103 and paragraphs

[0080] to

[0081] of Japanese Patent Publication No. 2010-215608. Among these specific examples, aryl sulfonate type or alkanesulfonate type photoacid generators are preferred because they generate an acid of appropriate strength for deprotecting the acid-unstable group of the repeating unit represented by formula (A5).

[0060] As such a photoacid generator, salt compounds having an anion with the structure shown below are preferred. [ka]

[0061] [ka]

[0062] [ka]

[0063] [ka]

[0064] [ka]

[0065] [ka]

[0066] [ka]

[0067] [ka]

[0068] As the photoacid generator for component (B), a salt compound containing an anion represented by the following formula (B-1) is preferred. [ka]

[0069] In equation (B-1), m is either 0 or 1. p is an integer between 1 and 3. q is an integer between 1 and 5. r is an integer between 0 and 3.

[0070] In formula (B-1), L 1 These are single bonds, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds.

[0071] In formula (B-1), L 2 These are ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds.

[0072] In formula (B-1), Y 1When p is 1, it is a single bond or a hydroxylene group having 1 to 20 carbon atoms, and when p is 2 or 3, it is a (p+1) valent hydrocarbon group having 1 to 20 carbon atoms. The hydroxylene group and the (p+1) valent hydrocarbon group may contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxyl group, and a carboxyl group.

[0073] Y 1 The hydroxylene group, represented by , having 1 to 20 carbon atoms, can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, etc. Examples include alkanediyl groups with 1 to 20 carbon atoms; cyclic saturated hydrocarbylene groups with 3 to 20 carbon atoms such as cyclopentanediyl, cyclohexanediyl, norbornanediyl, and adamantanediyl; unsaturated aliphatic hydrocarbylene groups with 2 to 20 carbon atoms such as vinylene and propene-1,3-diyl; arylene groups with 6 to 20 carbon atoms such as phenylene and naphthylene; and groups obtained by combining these. Also, Y 1 The (p+1) valent hydrocarbon group having 1 to 20 carbon atoms, represented by , may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include groups obtained by removing one or two hydrogen atoms from the aforementioned specific examples of the 1 to 20 carbon atom hydrocarbylene group.

[0074] In formula (B-1), Rf 1 and Rf 2 Each of these is independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one is either a fluorine atom or a trifluoromethyl group.

[0075] In formula (B-1), R11 This includes a hydroxyl group, a carboxyl group, a saturated hydrocarbyl group with 1 to 6 carbon atoms, a saturated hydrocarbyloxy group with 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group with 2 to 6 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, an amino group, and -N(R 11A )-C(=O)-R 11B or -N(R 11A )-C(=O)-OR 11B And R 11A R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 11B This is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms.

[0076] R 11 , R 11A and R 11B The saturated hydrocarbyl group having 1 to 6 carbon atoms, represented by R, may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, and n-hexyl groups; and cyclic saturated hydrocarbyl groups having 3 to 6 carbon atoms such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl groups. 11 The saturated hydrocarbyl portion of the saturated hydrocarbyloxy group having 1 to 6 carbon atoms, as represented by R, is the same as the specific examples of saturated hydrocarbyl groups mentioned above. 11 Examples of the saturated hydrocarbyl portion of the saturated hydrocarbyl carbonyloxy group having 2 to 6 carbon atoms, as described above, include those having 1 to 5 carbon atoms.

[0077] R 11BThe carbon-2-carbon unsaturated aliphatic hydrocarbyl groups represented by can be linear, branched, or cyclic. Specific examples include carbon-2-carbon alkenyl groups such as vinyl, propenyl, butenyl, and hexenyl groups; carbon-2-carbon alkynyl groups such as ethynyl, propynyl, and butynyl groups; and carbon-3-carbon cyclic unsaturated aliphatic hydrocarbyl groups such as cyclohexenyl and norbornenyl groups.

[0078] In formula (B-1), R 12 This is a saturated hydrocarbylene group having 1 to 20 carbon atoms or an arylene group having 6 to 14 carbon atoms, wherein some or all of the hydrogen atoms of the saturated hydrocarbylene group may be substituted with halogen atoms other than fluorine atoms, and some or all of the hydrogen atoms of the arylene group may be substituted with substituents selected from a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, a halogen atom, and a hydroxyl group.

[0079] R 12 The saturated hydrocarbylene groups having 1 to 20 carbon atoms, represented by , can be linear, branched, or cyclic. Specific examples include alkane diyl groups having 1 to 20 carbon atoms, such as methanediyl, ethane-1,1-diyl, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, decane-1,10-diyl, undecane-1,11-diyl, and dodecane-1,12-diyl; cyclic saturated hydrocarbylene groups having 3 to 20 carbon atoms, such as cyclopentanediyl, cyclohexanediyl, norbornanediyl, and adamantanediyl; and groups obtained by combining these.

[0080] R 12Specific examples of arylene groups with 6 to 14 carbon atoms, represented by , include phenylene groups, naphthylene groups, phenanthrendiyl groups, and anthracenediyl groups. The hydrocarbyl portion of the saturated hydrocarbyl group having 1 to 20 carbon atoms and the hydrocarbyloxy group having 1 to 20 carbon atoms, which are substituents on the arylene group, may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 20 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl groups; and cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups. Specific examples of arylene groups having 6 to 14 carbon atoms that are substituents on the aforementioned arylene group include phenylene group, naphthylene group, phenanthrendiyl group, anthracenediyl group, and the like.

[0081] The anion is more preferably represented by the following formula (B-2). [ka]

[0082] In formula (B-2), p, q, r, L 1 , Y 1 and R 11 The same as above. n is an integer from 1 to 4. 12A R is a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, a halogen atom, or a hydroxyl group. When n is 2, 3, or 4, each R 12A They may be the same as or different from each other.

[0083] The anions represented by formula (B-1) include, but are not limited to, those listed below. [ka]

[0084] [ka]

[0085] [ka]

[0086] [ka]

[0087] [ka]

[0088] [ka]

[0089] [ka]

[0090] [ka]

[0091] [ka]

[0092] [ka]

[0093]

change

[0094]

change

[0095]

change

[0096]

change

[0097]

change

[0098]

change

[0099]

change

[0100]

change

[0101]

change

[0102]

change

[0103]

change

[0104]

Chem.

[0105]

Chem.

[0106]

Chem.

[0107]

Chem.

[0108]

Chem.

[0109]

Chem.

[0110]

Chem.

[0111] As the cation that forms a pair with the anion, a sulfonium cation represented by the following formula (B-3) or an iodonium cation represented by the following formula (B-4) is preferable.

Chem.

[0112] In formulas (B-3) and (B-4), R 31 ~R 35 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom.

[0113] R 31 ~R 35 Examples of the halogen atom represented by 35 include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.

[0114] R 31 ~R 35 The hydrocarbyl group having 1 to 20 carbon atoms represented by 35 may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, tert-pentyl group, n-pentyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, etc.; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group, norbornyl group, tricyclo[5.2.1.0 2,6 decanyl group, adamantyl group, adamantylmethyl group, etc.; aryl groups having 6 to ...... 20 carbon atoms such as phenyl group, naphthyl group, anthracenyl group, etc. Further, part or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., and a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc. may be interposed between the carbon-carbon bonds of the hydrocarbyl group. As a result, it may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc.

[0115] Also, R 31 and R 32 may combine with each other to form a ring together with the sulfur atom to which they are attached. Examples of the ring formed at this time include those shown below.

Chemical formula

[0116] Specific examples of sulfonium cations represented by formula (B-3) are listed below, but are not limited to these. [ka]

[0117] [ka]

[0118] [ka]

[0119] [ka]

[0120] [ka]

[0121] [ka]

[0122] [ka]

[0123] [ka]

[0124] [ka]

[0125]

change

[0126]

change

[0127]

change

[0128]

change

[0129]

change

[0130]

change

[0131]

change

[0132]

change

[0133]

change

[0134]

change

[0135]

change

[0136] [ka]

[0137] [ka]

[0138] Specific examples of iodonium cations represented by formula (B-4) are listed below, but are not limited to these. [ka]

[0139] [ka]

[0140] The acid generated by the photoacid generator preferably has a pKa of -2.0 or higher, and more preferably -1.0 or higher. Furthermore, the upper limit of the pKa is preferably 2.0. The pKa values ​​were calculated using the pKa DB in the ACD / Chemsketch ver:9.04 software from Advanced Chemistry Development, Inc.

[0141] In the chemically amplified positive resist composition of the present invention, the content of the photoacid generator is preferably 1 to 30 parts by mass, and more preferably 2 to 20 parts by mass, per 80 parts by mass of the (A) base polymer. The photoacid generator may be used alone or in combination of two or more types.

[0142] [(C) Quencher] The chemically amplified positive resist composition of the present invention contains a quencher (acid diffusion inhibitor). Examples of the quencher include conventional basic compounds. Examples of conventional basic compounds include primary, secondary, and tertiary aliphatic amines, hybrid amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxyl group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, carbamates, and the like. In particular, primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of Japanese Patent Publication No. 2008-111103, especially amine compounds having a hydroxyl group, ether bond, ester bond, lactone ring, cyano group, or sulfonic acid ester bond, or compounds having a carbamate group described in Japanese Patent No. 3790649, are preferred. Preferred examples include tris[2-(methoxymethoxy)ethyl]amine, tris[2-(methoxymethoxy)ethyl]amine-N-oxide, dibutylaminobenzoic acid, morpholine derivatives, and imidazole derivatives. By adding such basic compounds, it is possible to further suppress the diffusion rate of the acid in the resist film or correct its shape, for example.

[0143] Furthermore, examples of the quencher include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of carboxylic acids whose α-position is not fluorinated, as described in Japanese Patent Publication No. 2008-158339. Sulfonic acids, imido acids, or methidic acids with α-position fluorinated are necessary for deprotecting acid-unstable groups, but salt exchange with onium salts whose α-position is not fluorinated releases carboxylic acids whose α-position is not fluorinated. Carboxylic acids whose α-position is not fluorinated hardly undergo deprotection reactions and therefore function as quenchers.

[0144] Examples of onium salts of carboxylic acids whose α-position is not fluorinated include those represented by the following formula (C1). [ka]

[0145] In formula (C1), R 41 This refers to a hydrocarbyl group having 1 to 40 carbon atoms, which may contain hydrogen atoms or heteroatoms, but excludes those in which the hydrogen atom bonded to the carbon atom at the α position of the carboxyl group is substituted with a fluorine atom or a fluoroalkyl group.

[0146] R 41 The hydrocarbyl group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 40 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0 2,6 ] Cyclic saturated hydrocarbyl groups with 3 to 40 carbon atoms, such as decanyl group, adamantyl group, and adamantylmethyl group; alkenyl groups with 2 to 40 carbon atoms, such as vinyl group, allyl group, propenyl group, butenyl group, and hexenyl group; cyclic unsaturated aliphatic hydrocarbyl groups with 3 to 40 carbon atoms, such as cyclohexenyl group; phenyl group, naphthyl group, alkylphenyl group (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-methylmethylphenyl group, 4-methylphenyl group, methylphenyl group, methylphenyl group, 4-methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, Examples include aryl groups with 6 to 40 carbon atoms, such as t-butylphenyl group, 4-n-butylphenyl group, dialkylphenyl group (2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group, etc.), alkylnaphthyl group (methylnaphthyl group, ethylnaphthyl group, etc.), and dialkylnaphthyl group (dimethylnaphthyl group, diethylnaphthyl group, etc.); and aralkyl groups with 7 to 40 carbon atoms, such as benzyl group, 1-phenylethyl group, and 2-phenylethyl group.

[0147] Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom, or halogen atom, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, and as a result, it may contain a hydroxyl group, a cyano group, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc. Examples of hydrocarbyl groups containing heteroatoms include heteroaryl groups such as thienyl groups; alkoxyphenyl groups such as 4-hydroxyphenyl, 4-methoxyphenyl, 3-methoxyphenyl, 2-methoxyphenyl, 4-ethoxyphenyl, 4-tert-butoxyphenyl, and 3-tert-butoxyphenyl groups; alkoxynaphthyl groups such as methoxynaphthyl, ethoxynaphthyl, n-propoxynaphthyl, and n-butoxynaphthyl groups; dialkoxynaphthyl groups such as dimethoxynaphthyl and diethoxynaphthyl groups; and aryloxoalkyl groups such as 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl, 2-(1-naphthyl)-2-oxoethyl, and 2-(2-naphthyl)-2-oxoethyl groups.

[0148] In formula (C1), Mq + This is an onium cation. The onium cation is preferably a sulfonium cation, an iodonium cation, or an ammonium cation, and more preferably a sulfonium cation or an iodonium cation. Specific examples of the sulfonium cation include those similar to those exemplified as the sulfonium cation represented by formula (B-3). Specific examples of the iodonium cation include those similar to those exemplified as the iodonium cation represented by formula (B-4).

[0149] The anions of the onium salt represented by formula (C1) include, but are not limited to, those listed below. [ka]

[0150] [ka]

[0151] [ka]

[0152] As the quencher, a sulfonium salt of an iodized benzene ring-containing carboxylic acid represented by the following formula (C2) can also be suitably used. [ka]

[0153] In equation (C2), s is an integer between 1 and 5, t is an integer between 0 and 3, and u is an integer between 1 and 3.

[0154] In formula (C2), R 51 This may be a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, or -N(R 51A )-C(=O)-R 51B Or -N(R 51A )-C(=O)-OR 51B That is. R 51A R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 51B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. When t and / or u are 2 or more, each R 51 They may be the same or different from one another.

[0155] In formula (C2), L11 This is a single bond or a (u+1) valent linking group having 1 to 20 carbon atoms, and may contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxyl group, and a carboxyl group. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, and saturated hydrocarbylsulfonyloxy group may be linear, branched, or cyclic.

[0156] In formula (C2), R 52 , R 53 and R 54 Each of these is a C1-C20 hydrocarbyl group which may independently contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C20 alkyl groups, C2-C20 alkenyl groups, C6-C20 aryl groups, C7-C20 aralkyl groups, etc. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a hydroxyl group, carboxyl group, halogen atom, oxo group, cyano group, nitro group, sultone ring, sulfo group, or sulfonium salt-containing group, and some of the -CH2- of the hydrocarbyl group may be substituted with an ether bond, ester bond, carbonyl group, amide bond, carbonate bond, or sulfonic acid ester bond. 52 and R 53 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded.

[0157] A specific example of the compound represented by formula (C2) is the one described in Japanese Patent Publication No. 2017-219836. The compound represented by formula (C2) exhibits high absorption, high sensitization effect, and high acid diffusion inhibition effect.

[0158] As the quencher, a nitrogen atom-containing carboxylate compound represented by the following formula (C3) can also be used. [ka]

[0159] In formula (C3), R 61 ~R 64 These are, independently, hydrogen atoms and -L 12 -CO2 - or a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. 61 and R 62 And, R 62 and R 63 or R 63 and R 64 These may bond with each other to form a ring with the carbon atom to which they are bonded. 12 R is a hydroxylene group having 1 to 20 carbon atoms, which may contain single bonds or heteroatoms. 65 This is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a hydrogen atom or a heteroatom.

[0160] In formula (C3), ring R is a ring having 2 to 6 carbon atoms, including the carbon and nitrogen atoms in the formula, and some or all of the hydrogen atoms bonded to the carbon atoms of the ring are a hydrocarbyl group having 1 to 20 carbon atoms, or -L 12 -CO2 - The ring may be substituted with a sulfur atom, oxygen atom, or nitrogen atom. The ring may be an alicyclic ring or an aromatic ring, and is preferably a 5-membered or 6-membered ring. Specific examples include pyridine rings, pyrrole rings, pyrrolidine rings, piperidine rings, pyrazole rings, imidazoline rings, pyridazine rings, pyrimidine rings, pyrazine rings, imidazoline rings, oxazole rings, thiazole rings, morpholine rings, thiazine rings, triazole rings, and the like.

[0161] The onium carboxylate salt represented by formula (C3) contains at least one -L 12 -CO2 - It has a group. That is, R 61 ~R 64 At least one of them is -L 12 -CO2 - is and / or at least one hydrogen atom bonded to a carbon atom of ring R is -L12 -CO2 - It has been replaced with this.

[0162] In formula (C3), Q + This is a sulfonium cation, an iodonium cation, or an ammonium cation, but a sulfonium cation is preferred. Specific examples of the sulfonium cation include those similar to those exemplified as the sulfonium cation represented by formula (B-3).

[0163] The anions of the compound represented by formula (C3) include, but are not limited to, those listed below. [ka]

[0164] [ka]

[0165] [ka]

[0166] [ka]

[0167] [ka]

[0168] [ka]

[0169] Furthermore, a weak acidic betaine-type compound can also be used as the quencher. Specific examples are listed below, but are not limited to these. [ka]

[0170] As an example of the aforementioned quencher, a polymer-type quencher described in Japanese Patent Publication No. 2008-239918 can be cited. This enhances the rectangularity of the resist pattern by oriented on the surface of the resist film. The polymer-type quencher also has the effect of preventing film thinning of the pattern and rounding of the pattern top when a protective film for immersion lithography is applied.

[0171] In the chemically amplified positive resist composition of the present invention, the content of the quencher is preferably 0.01 to 50 parts by mass, and more preferably 0.1 to 40 parts by mass, per 80 parts by mass of the (A) base polymer. The quencher may be used alone or in combination of two or more types.

[0172] In the chemically amplified positive resist composition of the present invention, the ratio of the photoacid generator to the quencher ((B) / (C)) is less than 3 by mass, preferably less than 2.5, and more preferably less than 2. If the ratio of the photoacid generator to the quencher in the chemically amplified positive resist composition of the present invention is within the above range, acid diffusion can be sufficiently suppressed, and excellent resolution and dimensional uniformity can be obtained.

[0173] [(D) Fluorine atom-containing polymer] The chemically amplified positive resist composition of the present invention may contain a fluorine atom-containing polymer, which includes at least one selected from repeating units represented by the following formulas (D1), (D2), (D3), and (D4) (hereinafter also referred to as repeating units D1, D2, D3, and D4, respectively), and may further contain at least one selected from repeating units represented by the following formulas (D5) and (D6, respectively). The fluorine atom-containing polymer also functions as a surfactant, thus preventing the re-adhesion of insoluble matter to the substrate during the development process, and thus exhibiting an effect against development defects. [ka]

[0174] In formulas (D1) to (D6), R B These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. C Each of these is independently either a hydrogen atom or a methyl group. 101 , R 102 , R 104 and R 105 Each of these is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. 103 , R 106 , R 107 and R 108 Each of these is independently a hydrogen atom, a C1-C15 hydrocarbyl group, a C1-C15 fluorinated hydrocarbyl group, or an acid-unstable group, and R 103 , R 106 , R 107 and R 108 When is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between the carbon-carbon bonds.109 This is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a hydrogen atom or a group containing a heteroatom between the carbon-carbon bonds. 110 This is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a hydrogen atom or a group containing a heteroatom between the carbon-carbon bonds. 111 k is a saturated hydrocarbyl group having 1 to 20 carbon atoms, in which at least one hydrogen atom is substituted with a fluorine atom, and a portion of the -CH2- of the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. x is an integer from 1 to 3. y is an integer satisfying 0 ≤ y ≤ 5 + 2z - x. z is 0 or 1. k is an integer from 1 to 3. Z 1 This is a (k+1) valent hydrocarbon group having 1 to 20 carbon atoms or a (k+1) valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. 2 The bond is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain. 3 This is a single bond, -O-, *-C(=O)-OZ 31 -Z 32 -or *-C(=O)-NH-Z 31 -Z 32 - is Z 31 This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 A is a single bond, ester bond, ether bond, or sulfonamide bond. * indicates a bond with a carbon atom of the main chain.

[0175] In equations (D1) and (D2), R 101 , R 102 , R 104 and R 105Examples of saturated hydrocarbyl groups having 1 to 10 carbon atoms, represented by , include alkyl groups having 1 to 10 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl groups; and cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornyl groups. Of these, saturated hydrocarbyl groups having 1 to 6 carbon atoms are preferred.

[0176] In formulas (D1) to (D4), R 103 , R 106 , R 107 and R 108 Examples of C1-C15 hydrocarbyl groups represented by include C1-C15 alkyl groups, C2-C15 alkenyl groups, C2-C15 alkynyl groups, etc., but C1-C15 alkyl groups are preferred. Examples of the alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, etc. Examples of the alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, n-pentyl group, n-hexyl group, n-hexyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, etc. Examples of fluorinated hydrocarbyl groups include groups in which some or all of the hydrogen atoms bonded to the carbon atoms of the hydrocarbyl group mentioned above are substituted with fluorine atoms.

[0177] In formula (D4), Z 1 Examples of (k+1) valent hydrocarbon groups having 1 to 20 carbon atoms, represented by , include alkyl groups with 1 to 20 carbon atoms or cyclic saturated hydrocarbyl groups with 3 to 20 carbon atoms from which k hydrogen atoms have been removed. Also, Z 1 Examples of k+1 valent fluorinated hydrocarbon groups having 1 to 20 carbon atoms, as represented by the formula, include groups in which at least one hydrogen atom of the aforementioned (k+1) valent hydrocarbon group is substituted with a fluorine atom.

[0178] Specific examples of repeating units D1 to D4 are shown below, but are not limited to these. Note that in the following formula, R B This is the same as described above. [ka]

[0179] [ka]

[0180] [ka]

[0181] In formula (D5), R 109 and R 110 Examples of C1-C5 hydrocarbyl groups represented by include alkyl groups, alkenyl groups, and alkynyl groups, but alkyl groups are preferred. Examples of the alkyl groups include methyl groups, ethyl groups, n-propyl groups, isopropyl groups, n-butyl groups, isobutyl groups, sec-butyl groups, and n-pentyl groups. In addition, groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms may be interposed between the carbon-carbon bonds of these groups.

[0182] In formula (D5), -OR 110 It is preferable that the group is hydrophilic. In this case, R 110 Preferred elements include hydrogen atoms, C1-C5 alkyl groups with oxygen atoms interposed between carbon-carbon bonds, etc.

[0183] In formula (D5), Z 2 It is preferable that *-C(=O)-O- or *-C(=O)-NH-. Furthermore, R C It is preferable that it is a methyl group. 2 The presence of a carbonyl group improves the acid trapping ability derived from the antistatic film. Also, R CWhen the group is a methyl group, a more rigid polymer with a higher glass transition temperature (Tg) is formed, thus suppressing acid diffusion. This results in good temporal stability of the resist film, and the resolution and pattern shape do not deteriorate.

[0184] The repeating unit D5 can be, but is not limited to, the following. Note that in the following formula, R C This is the same as described above. [ka]

[0185] [ka]

[0186] In formula (D6), Z 3 The saturated hydrocarbylene group having 1 to 10 carbon atoms, represented by , may be linear, branched, or cyclic. Specific examples include methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-1,3-diyl group, propane-2,2-diyl group, butane-1,1-diyl group, butane-1,2-diyl group, butane-1,3-diyl group, butane-2,3-diyl group, butane-1,4-diyl group, and 1,1-dimethylethane-1,2-diyl group.

[0187] In formula (D6), R 111 A saturated hydrocarbyl group having 1 to 20 carbon atoms, represented by , in which at least one hydrogen atom is substituted with a fluorine atom, may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 20 carbon atoms or cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom.

[0188] The repeating unit D6 can be, but is not limited to, the following. Note that in the following formula, R C This is the same as described above. [ka]

[0189] [ka]

[0190] [ka]

[0191] [ka]

[0192] The content of repeating units D1 to D4 is preferably 15 to 95 mol%, and more preferably 20 to 85 mol%, of the total repeating units of the fluorine atom-containing polymer. The content of repeating units D5 and / or D6 is preferably 5 to 85 mol%, and more preferably 15 to 80 mol%, of the total repeating units of the fluorine atom-containing polymer. Repeating units D1 to D6 may be used individually or in combination of two or more types.

[0193] The fluorine atom-containing polymer may contain other repeating units besides those described above. Examples of such repeating units include those described in paragraphs

[0046] to

[0078] of Japanese Patent Application Publication No. 2014-177407. If the fluorine atom-containing polymer contains other repeating units, the content thereof is preferably 50 mol% or less of the total repeating units of the fluorine atom-containing polymer.

[0194] The aforementioned fluorine atom-containing polymer can be synthesized by copolymerizing each monomer, which is optionally protected with a protecting group, using known methods, and then performing a deprotection reaction as necessary. The copolymerization reaction is not particularly limited, but radical polymerization and anionic polymerization are preferred. For these methods, refer to Japanese Patent Application Publication No. 2004-115630.

[0195] The Mw of the fluorine atom-containing polymer is preferably 2000 to 50000, and more preferably 3000 to 20000. If the Mw is less than 2000, it may promote acid diffusion, leading to a deterioration in resolution and impaired stability over time. If the Mw is too high, the solubility in the solvent will decrease, potentially causing coating defects. Furthermore, the Mw / Mn of the fluorine atom-containing polymer is preferably 1.0 to 2.2, and more preferably 1.0 to 1.7.

[0196] When the chemically amplified positive resist composition of the present invention contains the fluorine atom-containing polymer, its content is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, and even more preferably 0.5 to 10 parts by mass, per 80 parts by mass of the (A) base polymer. The fluorine atom-containing polymer may be used alone or in combination of two or more types.

[0197] [(E) Organic solvents] The chemically amplified positive resist composition of the present invention may contain an organic solvent. The organic solvent is not particularly limited as long as it can dissolve each component. Examples of such organic solvents include ketones such as cyclohexanone and methyl-2-n-pentyl ketone, as described in paragraphs

[0144] to

[0145] of Japanese Patent Application Publication No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, and ethylene glycol Examples include ethers such as monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as PGMEA, propylene glycol monoethyl ether acetate, ethyl lactate (EL), ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate; lactones such as γ-butyrolactone; and mixed solvents thereof. When using acetal-based acid-unstable groups, high-boiling point alcohol-based solvents, specifically diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, and 1,3-butanediol, can be added to accelerate the deprotection reaction of the acetal.

[0198] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, PGME, cyclohexanone, EL, γ-butyrolactone, and mixtures thereof are preferred.

[0199] When the chemically amplified positive resist composition of the present invention contains the organic solvent, its content is preferably 200 to 10,000 parts by mass, and more preferably 400 to 5,000 parts by mass, per 80 parts by mass of the (A) base polymer. The organic solvent may be used alone or as a mixture of two or more.

[0200] [(F) Surfactants] The chemically amplified positive resist composition of the present invention may contain a commonly used surfactant to improve its applicability to the substrate. When using a surfactant, many are known, as numerous examples are described in Japanese Patent Application Publication No. 2004-115630, and can be selected by referring to them. When the chemically amplified positive resist composition of the present invention contains the surfactant, its content is preferably 0 to 5 parts by mass per 80 parts by mass of the (A) base polymer. The surfactant may be used alone or in combination of two or more types. If the chemically amplified positive resist composition of the present invention contains the fluorine atom-containing polymer, the fluorine atom-containing polymer also acts as a surfactant, so the surfactant may not be included.

[0201] The chemically amplified positive resist composition of the present invention can be prepared by dissolving components (A) to (C), and optionally components (D) and (F), simultaneously or in any order in the organic solvent of component (E), to obtain a homogeneous resist solution. The obtained resist solution is preferably filtered. By using nylon or polyethylene (PE) as the filter for filtration, gel components and particles contained in the resist solution can be effectively removed. Furthermore, it is preferable to use a filter with a pore size of 20 nm or less to maintain quality in the advanced generation.

[0202] In designing the chemically amplified positive-type resist composition of the present invention, the dissolution rate of the exposed portion of the resulting resist film in the alkaline developer is preferably 50 nm / sec or higher, and more preferably 80 nm / sec or higher, from the viewpoint of improving development loading. A dissolution rate of 50 nm / sec or higher allows for uniform dissolution in the alkaline developer even if there are differences in pattern layout in the dense / sparse pattern, thereby reducing linewidth fluctuations. The dissolution rate of the exposed portion in the present invention was calculated from the film loss when the chemically amplified positive-type resist composition of the present invention was spin-coated onto an 8-inch silicon wafer, baked at 110°C for 60 seconds to form a resist film with a thickness of 90 nm, exposed with KrF excimer laser light at an energy level sufficient to complete the polymer deprotection reaction, baked at 110°C for 60 seconds, and then developed at 23°C with a 2.38 mass% TMAH aqueous solution using a resist development analyzer.

[0203] Furthermore, the dissolution rate of the unexposed portion of the resist film obtained from the chemically amplified positive resist composition of the present invention in an alkaline developer is preferably 10 nm / min or less, more preferably 9 nm / min or less, and even more preferably 8 nm / min or less. When the resist film is in the thin film region (100 nm or less), the effect of pattern film reduction on the alkaline developer becomes large, and if the dissolution rate of the unexposed portion is greater than 10 nm / min, the pattern collapses, making it impossible to form a fine pattern. This is particularly noticeable in the fabrication of photomasks that require no defects, as the development process tends to be strong. The dissolution rate of the unexposed portion was calculated from the amount of film reduction when the chemically amplified positive resist composition of the present invention was spin-coated onto a 6-inch silicon wafer, baked at 110°C for 240 seconds to form a resist film with a thickness of 80 nm, and then developed in a 2.38 mass% TMAH aqueous solution at 23°C for 80 seconds.

[0204] [Method for forming a resist pattern] The resist pattern formation method of the present invention includes the steps of forming a resist film on a substrate using the chemically amplified positive-type resist composition described above, irradiating the resist film with a pattern using an EB (i.e., exposing the resist film using an EB), and developing the resist film irradiated with the pattern using an alkaline developer.

[0205] As the substrate, for example, substrates for integrated circuit manufacturing (Si, SiO, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coatings, etc.) or substrates for transmissive or reflective mask circuit manufacturing (Cr, CrO, CrON, MoSi2, Si, SiO, SiO2, SiON, SiONC, CoTa, NiTa, TaBN, SnO2, etc.) can be used. The chemically amplified positive resist composition is applied to the substrate by a method such as spin coating to a film thickness of 0.03 to 2 μm, and this is pre-baked on a hot plate, preferably at 60 to 150°C for 1 to 20 minutes, more preferably at 80 to 140°C for 1 to 10 minutes, to form a resist film.

[0206] Next, the resist film is exposed using an EB (electromagnetic beam) to irradiate a pattern. The energy of the EB is preferably 50-400 μC / cm² to form the desired pattern. 2 Irradiate in such a way that it results in the following.

[0207] In addition to conventional exposure methods, immersion

[0208] Next, post-exposure baking (PEB) is performed on a hot plate, preferably at 60-150°C for 1-20 minutes, more preferably at 80-140°C for 1-10 minutes.

[0209] Subsequently, the substrate is developed using a developer solution of an alkaline aqueous solution such as 0.1 to 5% by mass, preferably 2 to 3% by mass of TMAH, by conventional methods such as dipping, puddling, or spraying, preferably for 0.1 to 3 minutes, more preferably for 0.5 to 2 minutes, thereby forming the desired pattern on the substrate.

[0210] Furthermore, the chemically amplified positive resist composition of the present invention is particularly useful because it can form patterns with good isolated space resolution and a small LER. In addition, the chemically amplified positive resist composition of the present invention is particularly useful for pattern formation on substrates with surfaces that are prone to pattern peeling or pattern collapse due to the difficulty in achieving good adhesion of the resist pattern. Suitable substrates for this purpose include substrates in which a chromium compound containing one or more light elements selected from metallic chromium, oxygen, nitrogen, and carbon is sputtered onto the outermost surface, as well as SiO, SiO x Examples include substrates containing tantalum compounds, molybdenum compounds, cobalt compounds, nickel compounds, tungsten compounds, and tin compounds in their outermost layer. The chemically amplified positive resist composition of the present invention is particularly useful for pattern formation using a photomask blank as the substrate. In this case, the photomask blank may be either a transmissive or reflective type.

[0211] As a transmissive mask blank, a photomask blank having a light-shielding film made of a chromium-based material may be a photomask blank for binary masks or a photomask blank for phase-shift masks. In the case of a photomask blank for binary masks, the light-shielding film may consist of an anti-reflective layer and a light-shielding layer made of a chromium-based material, or the entire anti-reflective film on the surface side, or only the surface side of the anti-reflective film on the surface side, may be made of a chromium-based material, and the remaining part may consist of a silicon-based compound material which may contain, for example, a transition metal. In the case of a photomask blank for phase-shift masks, a photomask blank for phase-shift masks having a chromium-based light-shielding film on the phase-shift film may be considered.

[0212] The aforementioned photomask blank having a chromium-based material on the outermost layer is very well known, as exemplified in Japanese Patent Publication No. 2008-26500, Japanese Patent Publication No. 2007-302873, or as prior art in those publications. A detailed explanation will be omitted, but for example, when constructing a light-shielding film having an anti-reflective layer and a light-shielding layer using a chromium-based material, the following film configuration can be used.

[0213] When forming a light-shielding film having an anti-reflective layer and a light-shielding layer using a chromium-based material, the layer configuration may be such that the anti-reflective layer and the light-shielding layer are laminated in that order from the surface side, or the anti-reflective layer, light-shielding layer, and anti-reflective layer are laminated in that order. Furthermore, the anti-reflective layer and the light-shielding layer may each be multilayered, and the composition may change discontinuously or continuously between layers with different compositions. As for the chromium-based material to be used, metallic chromium and materials containing light elements such as oxygen, nitrogen, and carbon in metallic chromium can be used. Specifically, metallic chromium, chromium oxide, chromium nitride, chromium carbide, chromium oxide nitride, chromium carbide nitride, chromium oxide nitride, chromium oxide nitride, etc. can be used.

[0214] Furthermore, a reflective mask blank comprises a substrate, a multilayer reflective film formed on one of the main surfaces (front side) of the substrate, specifically a multilayer reflective film that reflects exposure light such as EUV light, and an absorber film formed on the multilayer reflective film, specifically an absorber film that absorbs exposure light such as EUV light and reduces reflectivity. A reflective mask (EUV reflective mask) having an absorber pattern (pattern of the absorber film) formed by patterning the absorber film is manufactured from the reflective mask blank (EUV reflective mask blank). The wavelength of EUV light used in EUV lithography is 13-14 nm, and is usually light with a wavelength of about 13.5 nm.

[0215] The multilayer reflective film is usually preferably provided in contact with one of the main surfaces of the substrate, but it is also possible to provide an underlayer film between the substrate and the multilayer reflective film, provided that the effects of the present invention are not lost. The absorber film may be formed in contact with the multilayer reflective film, but a protective film (protective film for the multilayer reflective film) may be provided between the multilayer reflective film and the absorber film, preferably in contact with the multilayer reflective film, and more preferably in contact with both the multilayer reflective film and the absorber film. The protective film is used to protect the multilayer reflective film during processing such as cleaning and correction. Furthermore, it is preferable that the protective film has the function of protecting the multilayer reflective film when the absorber film is patterned by etching, and preventing oxidation of the multilayer reflective film. On the other hand, a conductive film used for electrostatically chucking the reflective mask to the exposure apparatus may be provided under the other main surface (back surface), which is the surface opposite to one of the main surfaces of the substrate, preferably in contact with the other main surface. Here, one main surface of the substrate is referred to as the front and upper side, and the other main surface as the back and lower side. However, the front and back sides and top and bottom are defined for convenience only, and the one main surface and the other main surface are either of the two main surfaces (film-forming surfaces) on the substrate, and the front and back sides and top and bottom are interchangeable. More specifically, it can be formed by methods such as those exemplified as prior art in Japanese Patent Application Publication No. 2021-139970 or therein.

[0216] According to the resist pattern formation method of the present invention, even when a substrate (for example, a transmissive or reflective mask blank) is used in which the outermost surface is made of a material that easily affects the resist pattern shape, such as a material containing chromium, silicon, or tantalum, a pattern with high resolution and small dimensional differences that are independent of pattern density and suppress the effects of development loading and residue defects can be obtained. [Examples]

[0217] The present invention will be specifically described below with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples. The copolymerization composition ratio is expressed as a molar ratio, and Mw is the weight-average molecular weight equivalent to polystyrene as measured by GPC.

[0218] [1] Polymer synthesis [Synthesis Example] Synthesis of Polymer P-1 20 g of polyhydroxystyrene-acenaphthylene copolymer and 46.7 g of THF as a solvent were added to a 100 mL flask. To this reaction solution, 0.5 g of methanesulfonic acid was added under a nitrogen atmosphere at approximately 25°C, followed by the dropwise addition of 4.4 g of 1-methoxy-2-methylpropene, and the reaction was allowed to proceed at room temperature for 4.5 hours. After the reaction was complete, 1.0 g of triethylamine was added, and the resulting reaction solution was added dropwise to 500 g of hexane. The precipitated copolymer was filtered off. The filtered copolymer was washed twice with 120 g of hexane. The obtained copolymer was dissolved in a mixed solvent of 60 g of ethyl acetate and 20 g of water. The resulting solution was transferred to a separatory funnel, 0.7 g of acetic acid was added, and the separation was performed. The lower layer was removed, and 20 g of water and 0.9 g of pyridine were added to the resulting organic layer, and the separation was performed again. The lower layer was removed, and 20 g of water was added to the resulting organic layer for further washing and separation (a total of 5 washing and separation steps were performed). After concentrating the organic layer following liquid-liquid separation, it was dissolved in 40 g of PGME. The resulting solution was added dropwise to 600 g of water, and the resulting precipitate was filtered off. After washing with water and drying, 20.3 g of the target polymer P-1, a white polymer, was obtained. 13 C-NMR, 1 The following analysis results were obtained by measuring using H-NMR and GPC. [ka]

[0219] Furthermore, polymers P-2 to P-17, comparative polymers cP-1 to cP-6, and AP-1 to AP-6 were synthesized using the same methods as those described in the above synthesis examples and known methods, except for changes in the type and mixing ratio of each monomer.

[0220] [ka]

[0221] [ka]

[0222] [ka]

[0223] [ka]

[0224] [ka]

[0225] [ka]

[0226] [ka]

[0227] The dissolution rate of the polymer in the alkaline developer was calculated by spin-coating an 8-inch silicon wafer with the polymer solution (polymer concentration: 16.7 mass%, solvent: PGMEA), baking it at 100°C for 90 seconds to form a film with a thickness of 1000 nm, and then developing it in a 2.38 mass% TMAH aqueous solution at 23°C for 100 seconds, measuring the amount of film loss. As a result, the dissolution rates of P-1 to P-17, AP-1 to AP-6, and cP-2 to cP-6 were 5 nm / min or less, and the dissolution rate of cP-1 was 14 nm / min.

[0228] [2] Preparation of chemically amplified positive resist compositions [Examples 1-1 to 1-37, Comparative Examples 1-1 to 1-7] Chemically amplified positive resist compositions were prepared by dissolving each component in an organic solvent in the compositions shown in Tables 1 to 3 below, and filtering the resulting solutions through a 5 nm nylon filter and a 1 nm UPE filter. The organic solvent was a mixed solvent consisting of 940 parts by mass of PGMEA, 1870 parts by mass of EL, and 1870 parts by mass of PGME.

[0229] The dissolution rate of the resist composition in an alkaline developer was calculated by spin-coating an 8-inch silicon wafer, baking it at 110°C for 240 seconds to form a resist film with a thickness of 80 nm, and then developing it in a 2.38 mass% TMAH aqueous solution at 23°C for 80 seconds, measuring the amount of film loss. As a result, the dissolution rates of the resist films obtained from resist compositions R-1 to R-37, CR-1, and CR-3 to CR-7 were 10 nm / min or less, and the dissolution rate of the resist film obtained from resist composition CR-2 was 17 nm / min.

[0230] [Table 1]

[0231] [Table 2]

[0232] [Table 3]

[0233] The structures of the photoacid generators PAG-1 to PAG-5, quenchers Q-1 to Q-4, and fluorine atom-containing polymers D-1 to D-5 in Tables 1 to 3 are as follows. [ka]

[0234] [ka]

[0235] [ka]

[0236] [3] EB lithography evaluation [Examples 2-1 to 2-37, Comparative Examples 2-1 to 2-7] Each chemically amplified positive resist composition (R-1 to R-37, CR-1 to CR-7) was spin-coated onto a reflective mask blank for EUV exposure using ACT-M (manufactured by Tokyo Electron Ltd.). The blank consisted of a 284 nm thick Mo / Si 40-layer multilayer reflective film, a 3.5 nm thick Ru film as a protective layer, a 70 nm thick TaN film as an absorption layer, and a 6 nm thick CrN film as a hard mask. The mask blank was then pre-baked on a hot plate at 110°C for 600 seconds to produce an 80 nm thick resist film. The thickness of the obtained resist film was measured using an optical measuring instrument, NanoSpec (manufactured by Nanometrics). Measurements were taken at 81 locations within the plane of the blank substrate, excluding the outer edge portion up to 10 mm inward from the outer edge, and the average thickness and thickness range were calculated.

[0237] Furthermore, the resist film was exposed using an EB exposure system (EBM-5000plus manufactured by Newflare Technology Co., Ltd., accelerating voltage 50kV), subjected to PEB at 110°C for 600 seconds, and developed with a 2.38 mass% TMAH aqueous solution to obtain a positive type pattern.

[0238] The obtained resist patterns were evaluated as follows: The fabricated patterned mask blanks were observed using an overhead SEM (scanning electron microscope), and the optimal exposure amount (μC / cm²) was determined to resolve 200 nm 1:1 line-and-space (LS) lines at a 1:1 ratio. 2 The resolution (limiting IS resolution) was defined as the minimum dimension at the exposure dose that resolves a 200nm isolated space (IS) at a 9:1 ratio, and the LER of a 200nm LS was measured by SEM. For development loading evaluation, the exposure dose (μC / cm²) that resolves a 1:1 LS of the design 200nm at a 1:1 ratio was defined within the substrate surface. 2 The dimensions of the space between a 200nm LS pattern formed using ( ) and a 200nm LS pattern with dummy patterns of densities of 15%, 25%, 33%, 45%, 50%, 55%, 66%, 75%, 85%, and 95% placed around the pattern were measured by SEM, and the difference in dimensional differences between the dense and sparse patterns was compared. The pattern shape was determined visually to determine whether it was rectangular or not.

[0239] The dissolution rate of the exposed area is determined by spin-coating a resist solution onto an 8-inch silicon wafer, baking it at 110°C for 60 seconds to form a resist film with a thickness of 90 nm, and then applying an exposure dose (mJ / cm²) that resolves a 200 nm 1:1 line and space (LS) at a 1:1 ratio. 2 Exposure was performed using KrF excimer laser light, followed by baking at 110°C for 60 seconds. Then, the resist was developed using a resist development analyzer (RDA-800, manufactured by Lithotec Japan Co., Ltd.) with a 2.38 mass% TMAH aqueous solution at 23°C, and the results were calculated. The results are shown in Tables 4 and 5.

[0240] [Table 4]

[0241] [Table 5]

[0242] [4] Residue defect evaluation [Examples 3-1 to 3-6, Comparative Examples 3-1 to 3-5] The resist compositions (R-8, R-21, R-26, R-29, R-31, R-33, CR-1, CR-3~CR-6) were applied to a reflective mask blank for EUV exposure in the same manner as described above to form a resist film with a thickness of 80 nm. The resist film was then fully drawn using an EB exposure apparatus (EBM-5000plus, manufactured by Newflare Technology Co., Ltd., with an acceleration voltage of 50 kV) at the optimal exposure amount for each resist composition. PEB was applied at 110°C for 600 seconds, and the film was developed with a 2.38 mass% TMAH aqueous solution. The development residue was evaluated using a mask defect inspection device (M9650, manufactured by Lasertec Corporation). The total number of defects after development is shown in Table 6.

[0243] [Table 6]

[0244] The chemically amplified positive resist compositions (R-1 to R-37) of the present invention all exhibited good isolated space resolution, LER, and pattern rectangularity, and showed suppressed development loading. On the other hand, the comparative resist compositions (CR-1 to CR-5) showed a resolution of 50 μC / cm² for CR-1. 2 In the following sensitivity ranges, the energy level was not optimal, resulting in a tapered shape and degraded resolution. In CR-2, the dissolution rate of the unexposed areas of the polymer was high, resulting in a rounded top shape and degraded resolution. In CR-3 to CR-7, the base polymer design was insufficient, resulting in insufficient performance in terms of isolated space resolution, LER, and pattern rectangularity. Furthermore, in the residual defect evaluation, CR-1, CR-3 to CR-6 also showed insufficient performance. As a design of the present invention, by creating a resist composition in which the content ratio of the photoacid generator to the base polymer and quencher using a specific acetal-type acid-unstable group is controlled, it is believed that a pattern exhibiting good isolated space resolution, pattern shape, and LER even in the high-dose range was achieved, while suppressing the effects of development loading and residual defects.

[0245] The resist pattern formation method using the chemically amplified positive resist composition of the present invention is useful for semiconductor device manufacturing, particularly for photolithography in the processing of transmissive and reflective photomask blanks.

Claims

1. (A) Base polymer, (B) Photoacid generator, and (C) Quencher, with electron beam exposure at 50 μC / cm² 2 The above describes a chemically amplified positive resist composition for electron beam lithography, (A) The base polymer comprises a polymer containing a phenolic hydroxyl group-containing unit represented by the following formula (A1), an aromatic ring-containing unit represented by either the following formulas (A2) or (A4), and a phenolic hydroxyl group-containing unit protected by an acid-unstable group represented by the following formula (A5), wherein all repeating units of the polymer contained in the base polymer are repeating units having an aromatic ring skeleton. A chemically amplified positive resist composition in which the ratio of (B) photoacid generator to (C) quencher ((B) / (C)) is less than 3 by mass ratio. 【Chemistry 1】 (In the equation, a1 is an integer satisfying 0 ≤ a1 ≤ 5 + 2a3 - a2. a2 is an integer between 1 and 3. a3 is an integer between 0 and 2.) R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 The bond is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. The asterisk (*) is a bond to a carbon atom in the main chain. A 1 This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the saturated hydrocarbylene group is -CH 2 Some of the hyphens may be replaced with -O-. R 1 This is a halogen atom, a saturated hydrocarbyl carbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms that may be substituted with a halogen atom. 【Chemistry 2】 (In the formula, R A The same applies as above. b is an integer between 0 and 4. d1 is an integer between 0 and 5. d2 is an integer between 0 and 2. X 2 The bond is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. The asterisk (*) is a bond to a carbon atom in the main chain. A 2 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH 2 - of the saturated hydrocarbylene group may be substituted with -O-. R 2 This is a hydroxyl group, a halogen atom, a saturated hydrocarbyl carbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 8 carbon atoms that may be substituted with a halogen atom. R 4 This group is an acetyl group, a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxyhydrocarbyl group having 2 to 20 carbon atoms, a saturated hydrocarbylthiohydrocarbyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group, or a cyano group. If d2 is 1 or 2, it may also be a hydroxyl group. 【Transformation 3】 [(wherein, R A The same applies as above. e1 is an integer satisfying 0 ≤ e1 ≤ 5 + 2e3 - e2. e2 is an integer between 1 and 3. e3 is an integer between 0 and 2. X 3 The bond is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. The asterisk (*) is a bond to a carbon atom in the main chain. A 3 This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the saturated hydrocarbylene group is -CH 2 Some of the hyphens may be replaced with -O-. R 5 This is a halogen atom, a saturated hydrocarbyl carbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms that may be substituted with a halogen atom. R AL When e2 is 1, it is an acetal-type acid-unstable group represented by the following formula (A5-1), and when e2 is 2 or more, it is a hydrogen atom or an acetal-type acid-unstable group represented by the following formula (A5-1), but at least one of them is an acetal-type acid-unstable group represented by the following formula (A5-1). 【Chemistry 4】 (In the formula, R L1 and R L2 Each of these is independently a saturated hydrocarbyl group having 1 to 3 carbon atoms, and R L1 and R L2 However, they may bond with each other to form a ring with the carbon atoms to which they are bonded. L3 This is a hydrocarbyl group with 1 to 5 carbon atoms. The dashed lines represent bonding bonds.

2. The chemically amplified positive resist composition according to claim 1, wherein the phenolic hydroxyl group-containing unit is a repeating unit represented by the following formula (A1-1). 【Transformation 5】 (In the formula, R A (and a2 are the same as above.)

3. The chemically amplified positive resist composition according to claim 1, wherein the phenolic hydroxyl group-containing unit protected by the acid-unstable group is a repeating unit represented by the following formula (A5-2). 【Transformation 6】 (In the formula, R A , R L1 , R L2 and R L3 (This is the same as above.)

4. (B) The chemically amplified positive resist composition according to claim 1, wherein the acid strength (pKa) of the acid generated by the photoacid generator is -2.0 or higher.

5. (B) The chemically amplified positive resist composition according to claim 4, wherein the photoacid generator is an aryl sulfonate type or an alkane sulfonate type photoacid generator.

6. (B) The chemically amplified positive resist composition according to claim 4, wherein the photoacid generator is a salt compound containing an anion represented by the following formula (B-1). 【Transformation 7】 (In the formula, m is 0 or 1, p is an integer from 1 to 3, q ​​is an integer from 1 to 5, and r is an integer from 0 to 3.) L 1 These are single bonds, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds. L 2 These are ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds. Y 1 When p is 1, it is a single bond or a hydroxylene group having 1 to 20 carbon atoms, and when p is 2 or 3, it is a (p+1) valent hydrocarbon group having 1 to 20 carbon atoms. The hydroxylene group and the (p+1) valent hydrocarbon group may contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxyl group, and a carboxyl group. Rf 1 and Rf 2 Each of these is independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one is either a fluorine atom or a trifluoromethyl group. R 11 This includes a hydroxyl group, a carboxyl group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, an amino group, and -N(R) 11A )-C(=O)-R 11B or -N(R 11A )-C(=O)-O-R 11B And R 11A R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 11B This is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. R 12 This is a saturated hydrocarbylene group having 1 to 20 carbon atoms or an arylene group having 6 to 14 carbon atoms, wherein some or all of the hydrogen atoms of the saturated hydrocarbylene group may be substituted with halogen atoms other than fluorine atoms, and some or all of the hydrogen atoms of the arylene group may be substituted with substituents selected from a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, a halogen atom, and a hydroxyl group.

7. The chemically amplified positive resist composition according to claim 1, wherein (C) the quencher is an onium salt of a carboxylic acid whose α-position is not fluorinated, represented by the following formula (C1), a sulfonium salt of an iodized benzene ring-containing carboxylic acid represented by the following formula (C2), a nitrogen atom-containing carboxylate-type compound represented by the following formula (C3), or a betaine-type compound of a weak acid. 【Transformation 8】 (In the formula, R 41 This refers to a hydrocarbyl group having 1 to 40 carbon atoms, which may contain hydrogen atoms or heteroatoms, but excludes those in which the hydrogen atom bonded to the carbon atom at the α-position of the carboxyl group is substituted with a fluorine atom or a fluoroalkyl group. Mq + This is an onium cation. 【Chemistry 9】 (In the formula, s is an integer from 1 to 5, t is an integer from 0 to 3, and u is an integer from 1 to 3.) R 51 This may be a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, or -N(R) 51A )-C(=O)-R 51B Or -N(R 51A )-C(=O)-O-R 51B That is. R 51A R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 51B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. When t and / or u are 2 or more, each R 51 They may be the same or different from one another. L 11 This is a single bond or a (u+1) valent linking group having 1 to 20 carbon atoms, and may include at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxyl group, and a carboxyl group. R 52 , R 53 and R 54 Each of these is independently a C1-C20 hydrocarbyl group which may contain a halogen atom or a heteroatom. 52 and R 53 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. 【Chemistry 10】 (In the formula, R 61 ~R 64 These are, independently, hydrogen atoms and -L 12 -CO 2 - or a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. 61 and R 62 And, R 62 and R 63 And, or R 63 and R 64 These may bond with each other to form a ring with the carbon atoms to which they are bonded. 12 R is a hydroxylene group having 1 to 20 carbon atoms, which may contain single bonds or heteroatoms. 65 This is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a hydrogen atom or a heteroatom. Ring R is a ring having 2 to 6 carbon atoms, including the carbon and nitrogen atoms in the formula, and some or all of the hydrogen atoms bonded to the carbon atoms of the ring are a hydrocarbyl group having 1 to 20 carbon atoms, or -L 12 -CO 2 - The ring may be substituted with a sulfur atom, an oxygen atom, or a nitrogen atom. The onium carboxylate salt represented by formula (C3) contains at least one -L 12 -CO 2 - It has a base. Q + (These are sulfonium cations, iodonium cations, or ammonium cations.)

8. The chemically amplified positive resist composition according to claim 1, further comprising a fluorine atom-containing polymer that further comprises at least one selected from repeating units represented by the following formula (D1), repeating units represented by the following formula (D2), repeating units represented by the following formula (D3), and repeating units represented by the following formula (D4), and which may further comprise at least one selected from repeating units represented by the following formula (D5) and repeating units represented by the following formula (D6). 【Chemistry 11】 (In the formula, R B These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R C Each of these is independently either a hydrogen atom or a methyl group. R 101 , R 102 , R 104 and R 105 Each of these is independently either a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 、R 106 、R 107 and R 108 are each independently a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms or an acid-labile group, and when R 103 、R 106 、R 107 and R 108 are a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between carbon-carbon bonds. R 109 This is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a hydrogen atom or a group containing a heteroatom between the carbon-carbon bonds. R 110 This is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a hydrogen atom or a group containing a heteroatom between the carbon-carbon bonds. R 111 This is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and the saturated hydrocarbyl group is -CH 2 A portion of the - may be substituted with an ester bond or an ether bond. x is an integer between 1 and 3. y is an integer satisfying 0 ≤ y ≤ 5 + 2z - x. z is either 0 or 1. k is an integer between 1 and 3. Z 1 This is a (k+1) valent hydrocarbon group having 1 to 20 carbon atoms or a (k+1) valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. Z 2 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is a bond to a carbon atom of the main chain. Z 3 This is a single bond, -O-, *-C(=O)-O-Z 31 -Z 32 - or * - C (= O) - NH - Z 31 -Z 32 - is Z 31 This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 A is a single bond, ester bond, ether bond, or sulfonamide bond. * indicates a bond to a carbon atom in the main chain.

9. Furthermore, the chemically amplified positive resist composition according to claim 1, further comprising an organic solvent.

10. The chemically amplified positive resist composition according to claim 1, wherein the dissolution rate of the base polymer in an alkaline developer is 5 nm / min or less.

11. The chemically amplified positive-type resist composition according to claim 1, wherein the dissolution rate of the unexposed portion of the resist film obtained from the chemically amplified positive-type resist composition in an alkaline developer is 10 nm / min or less.

12. The chemically amplified positive-type resist composition according to claim 1, wherein the dissolution rate of the exposed portion of the resist film obtained from the chemically amplified positive-type resist composition in an alkaline developer is 50 nm / sec or more.

13. A resist pattern forming method comprising the steps of forming a resist film on a substrate using a chemically amplified positive-type resist composition according to any one of claims 1 to 12, irradiating the resist film with a pattern using an electron beam, and developing the resist film irradiated with the pattern using an alkaline developer, The exposure dose of the electron beam is 50 μC / cm 2 The above describes the resist pattern formation method.

14. The resist pattern forming method according to claim 13, wherein the outermost surface of the substrate is made of a material containing at least one selected from chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten, and tin.

15. The resist pattern forming method according to claim 13, wherein the substrate is a transmissive or reflective mask blank.

16. A transmissive or reflective mask blank coated with a chemically amplified positive resist composition according to any one of claims 1 to 12.

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